Effects of dietary sweet potato leaf meal on the growth, non-specific immune responses, total phenols and antioxidant capacity in channel catfish (Ictalurus punctatus)

Background Traditional energy sources in catfish diets have become costly, and economical alternatives are needed. Sweet potato leaves are underutilised agricultural by‐products that provide energy and substantial amounts of phenols, which affect animal and human health. There is little information on the effects of these compounds on catfish, or the capacity of catfish to accumulate dietary phenols. Catfish enriched with phenols have marketing potential as functional foods. This study investigated the effects of diets with sweet potato leaf meal (SPLM) on growth performance, health and total phenolic compounds in catfish. Results SPLM was substituted for wheat middlings in three diets fed to groups of juvenile catfish for 10 weeks. Weight gain, feed conversion, survival, alternative complement activity and lysozyme activity were similar among diets. Haematocrit was lower in fish fed diets with SPLM, but within the normal range. Total phenols and antioxidant capacity in the whole body were similar among treatments. Conclusion SPLM was an effective energy source for catfish up to the maximum level tested (230 g kg−1 diet). SPLM did not enhance total phenols in catfish, but there were no apparent antinutritional effects of the meal on catfish growth, health or survival.